It would take ​ (a)   years just to count to 7 billion.

• 200
• 2
• 20
• 2000

What was the world's population in 1800?

• 1 billion

• 2 billion

• 3 billion

• 4 billion

How many people are born every second?

• 1

• 2

• 5

• 10

What was the average life expectancy in 1960?

• 69 years

• 53 years

• 75 years

• 60 years

What is the life expectancy in 2025?

• 82 years
• 78 years

• 69 years

• 80 years

In 1975, the world's three megacities were New York, Tokyo, and ....

• Los Angeles
• Mexico City
• London
• Paris

As of 2025, with the global population now at 8 billion, how many megacities are there in the world?

• 21

• 40

• 31

• 37

What percentage of the world's population lacks adequate sanitation?

• 5%

• 13%

• 23%

• 38%

Seven billion people, speaking 7,000 languages, living in ..... countries.

• 194

• 300
• 250
• 150

So, the biggest challenge the world faces with a growing population is maintaining balance—between people, resources, and space. While the numbers may have decreased or increased in 2025, in your opinion, which one is the biggest problem - and why?
(Answer in 2 to 3 sentences)